Formaldimines and their reaction products



Patented Dec. 4, 1951 FORMALDIMINES AND THEIR REACTION PRODUCTS Howard D. Hartough, Pitman, N. J assignor to Socony-Vacuum Oil Company, Incorporated, a

corporation of New York No Drawing. Application October 29, 1947, Serial No. 782,962

8 Claims. ((11. 266-329) l The present invention relates to the preparation of formaldimines and, more particularly, to the preparation of thenylformaldimines.

It was found in mixing formaldehyde andammonium chloride solutions, the pH of each of resins. which is about 6, that the pH immediately It is to be noted that in the application for changed from 6 to less than 2, indicating forma- United States Letters Patent Serial No. 636,511, tion of hydrochloric acid or a Weaker base than filed December 21, 1945, now abandoned, in the ammonia. names of Howard D. Hartough and Sigmund J.

10 Lukasiewicsz these inventors described the pro- FHCI'FCHQWHw-NHFHCIJFEO duction of Z-thenylamine and di-(2-thenyl) Th s s a a o o t reactlon formaldeamine by mixing all reactants, i. e. thiophene, y and hydroxylflmme hydrochlolldeammonium halide and formaldehyde in contrast 2' NH 0H.HC1+CH O H C=NoH+HC1+H Q to'the procedure described hereinbefore.

While little is known of formaldimines in gene y op eral, imine structures are noted for their inwhen 2 methy1thiophen'e, f m ldehyd and sta'blhty and for their men reaetlvltyammonium halide are reacted at a temperature It has te found that by'careftmy coptrollmg not exceeding 56 degrees centigrade, a new comthe conditions of the reaction, simple intermepound having the empirical form l cqHssN can (hate N'tg'thenyntermaldlmmee can be e be isolated from the products of the reaction. vementltnroducei e eendltlens Very t Treatment of this compound with hot, dilute the lfeeetlvlty of the thlepheee eempeutld aqueous hydrogen chloride causes evolution of question and therefore the discussion W111 be f ld hyd Treatment f this compound dlYlded mte (A) thleptlene and (B) 2'methY1' with 2-methylthiophene and dilute aqueous hythlephenedrogen chloride yields a crystalline compound (A) Thwphene having a melting point of 217 to 218 degrees It has been found that when formaldehyde centigrade, which when mixed and melted with and ammonium chloride are stirred together at an authentic sample of di-(5-methyl-2-thenyD- room temperature for a period of not longer than amine hydrochloride caused no depression of the thirty minutes, the thiophene added, and the melting point of the authentic sample. On the mixture slowly warmed to 68 to '70 degrees centibasis of the foregoing reactions, the compound grade to initiate reaction, the source of heat having the empirical formula C-zHsSN has been immediately removed, and the temperature alassigned the following structure:

N-(5-methyl-2-thenyl)formaldimlne men 8 0H,N=0H, Inthe presenceof wile presence of 2-methylthiophene Hot dilute HCl and dilute HCl/ 4 \1 [met S calm-H01 H3O S flCHzNHzHC1+ onto Di-(5-niethyl-2-thenybamlne (5-methyl-2-theny1)- Formalhydrochloride amine hydrochloride dehyde lowed to-fall to ambient temperatures while the reaction is vigorously stirred, the chief products of the reaction are N-(2-thenyl)formaldimine,

'55 examples. 7

(B) that the reactivity of these compounds is such as to account for polymerization of simple thiophene amines with this compound to produce The compound was found to react with aniline in dilute hydrochloric acid solution, and with urea in phosphoric acid solution. V

Illustrative of conditions for the formation of formaldiamines are the following non-limiting 4 ture was maintained at about 25 C. for about 2 hours, warmed to 40 C., held at that temperature for about 30 minutes, cooled, neutralized with caustic soda and the formaldimine recovered as reactants a negative heat of solution was noted and the temperature fell to 15 C. and slowly rose to 23 C. About 2 moles ofthiophene were. then added and the reaction mixture stirred for one hour without any apparent. reaction, The.

in Example This product had asuliur content of 24.77 percent as compared to asulfur content of 25.60 per cent for N-(Z-thenyD'fOrmaIdimine.

Example III About 20 moles of formaldehyde as an aqueous 36 per cent formalin solution and about 20 moles of ammonium chloride were mixed. The mixture temperature was then raised. by increments of;

10 degrees and no reaction was observed until the temperature of the reaction mixture. reached about 70 C. At this temperature th'e'source off external heat was removed and the reaction mix-- ture stirred for about 3 hours until the reaction temperature fell to room temperature. The aqueous layer was decanted from-.the vthiophene layer which. represented about 1.3 moles. of thiophene. Accordingly, about 0.7, mole. of thiophene had: reacted. The aqueous layerwas neutralized with, aqueous 40 weight per cent sodium hydroxide solution, the light yellow oil .soireed dissolved in benzene and filtered, the benzeneremoved; by. distillation and: the residue subjected to..distillation at reduced pressure. A. distillate having. a.boiling range of ISO-200 C. at lmillimeters of mercury. pressure was obtained. The distillate. was a viscous, light yellow, oil that was semi-solid when cooled. When the distillate was treated with hot-dilute aqueoushydrogen chloride formaldehyde was evolved freely. The still residue after heating to 225 C. (pot temperature) during distillation, was light red in color, fluid and soluble in benzene. The'distillate contained 24.85 per cent sulfur and 10.97 per cent nitrogen and has been assigned the formula l e. a.

l= 2 s H N-(Z-thenyl) formaldimine, for which the calculated sulfur and nitrogen content isrespectively 25160 per cent and 11.20 per cent.

Thenitrog'en content of the still residue was '7.'7 6 per cent. While theforegoing procedure gives satisfac-v tory resultsit. is not essential tofollow the detailed operations set forth in Example I, The. critical procedure. di st i;r 1guis hing.from; that de- I scribed in application Serial No. 636,511Qisthat the mixture of thiophene, ammonium halide and formaldehyde is warmed to 68 to 70 C. and held at that temperature by any. suitable means of external cooling such as an icebat-h'until the heat of reaction has subsided. The temperature of the reaction mixture is thenallowed to drop to ambient temperature (15 -30 C.) instead'ofg refluxing the reaction mixture as described v.inJ

tenanceof temperatures of l5-30 C. leads to" the production of the f ormaldimine.

Example II About 0.1 mole of concentrated hydrochloric. acid was added to about 0.1 mole of 2-thenylamine in aqueous solution. To. thesolution of Z-thenylamine hydrochloride thus prep'ajredlwas. added about 0:15 mole" of formal'dehydqas "an? so formedwas stirred for about 30 minutes at aboutz25 C., and 10 moles of thiophene added. The reaction mixture was then warmed to C., andtheexternal source of heat removed. The reaction temperature was held at 70 C. by external cooling. After stirring for about 5 hours, the'mixtur'e was cooled to about 10 C., and the solid ammonium chloride removed. The remainder of thereaction mixture formed 2 layers;

an upperlayer of thiophene anda lower aqueous layer.

The thiophene layer wasgdistille'd and about 34 parts by weight-of still residue recovered. About 26.5 per cent of the still residue was 2-thenyl alcohol having a boiling point "of 3639 C. and a pressure of 0.9 millimeter mercury and a refractive index of n 1.5280 and about-23.5 per cent wasdi-(Z-thienyl)methane having. aboiling: point or -102 degrees centigrade; at a pressureof; 1. millimeter of mercury and a refractive index of n 1.5649.

An aliquot portion of the. aqueous layer was neutralized withv aqueoussodium hydroxide and. extracted with benzene. The benzene was then removed by evaporation. and a product containing a smallamount-ofibenzene obtained. Distilla'ti'on: of thisproductyielded about 34.8 per cent of N-(Z- 121 C., at a pressure of 3.7 millimeters of mercury and ,a refractivegindex;above n 1.595. (The product .Wastoo;viscous-fora more accurate e ermination):

- Eramplelv? Example IIl was repeated under the sameccnditions except that thereaction temperaturewas not allowed to rise above"65-C.

Example V Example III was again repeated with the following change, i. e. after initiating the reaction at 65-68 C., the temperature was lowered to 55 C., and maintained below that temperature throughout the reaction'period of about 5 hours. This produced a reaction mixture of vastly improved color, i. e. a pale yellow color.

Example VI A well-stirred mixture of about 980 parts by "weight of 2-methylthiophene (about 10 moles),

ride-(about ;15 moles) was warmed to40 C, The externalsource off heatwas removed andth reaction temperature was allowed. to rise to 55 C. and held at that temperature by external cooling. The di- (5-methyl-2 thenyl2 amine hydrochloride aqueous 36 per cent solution. The reaction'mix-t g was filtered off, washed with benzene, and the 5. crystals neutralized with aqueous caustic soda solution to obtain the free base.. The 5-methyl-2- thenylamine thus obtained was distilled. A yield of 369 parts by weight having a boiling point of 170-171 C. at a pressure of 8 millimeters and a refractive index of 1.5808 was obtained together with a still residue of about 50 parts by weight. Upon evaporation of the benzene washings of the amine hydrochloride, about 76 parts by weight of di- (5-methyl-2 -thienyl) methane,

was obtained.

Neutralization of the aqueous filtrate produced by the separation of the amine hydrochloride crystals from the reaction mixture followed by extraction of the neutralized filtrate with benzene, distillation of the benzene and distillation of the reaction products in vacuum produced the following products:

Pts. by Product Weight Boiling Point 5-methyl-2-thenylalcohol l1 4247 0., 6 mm. Hg. 5-methyl-2-thenylamine- 44 80-85" 0., 6 mm. Hg. N-(5-methyl-2-theny1)for- 1 134 128133 0., 4 mm. Hg.

maldimine. di-(5-methyl-2-thenyl)- 70 159 C., 4 mm.

amine Residue 145 1 Recrystallized from alcohol, melting point 83.5-84.5 C. 1 my 1.5808.

Treatment of the N-(5-methyl-2-thenyl) formaldimine with hot dilute aqueous hydrochloric acid caused evolution of formaldehyde.

N- S-methyI-Z-phenyl) formaldlmine When the foregoing product, C'IHQSN is reacted with acetic anhydride in the ASTM test for hydroxyl number, the hydroxyl number is 620.

Example VII Seven parts by weight v of N-(5-methyl-2- thenyl) formaldimine' were dissolved in 15 parts by weight of water and 5 parts by weight of hydrochloric acid. The amine hydrochloride thus formed in aqueous solution was vigorously stirred with 5 parts by weight of 2-methylthiophene and heated to 70-75 C. for about 15 minutes and allowed to cool. A white crystalline product was formed which was'separated, dried and recrystallized from 35 parts by weight of water. After drying, these crystals melted at 218-219 C. A mixed melting point with an authentic sample of di-(-methyl 2 thenyDamine hydrochloride (M. P. 218-219 C.) showed no depression.

Example VIII Aniline was reacted with the hydrochloride of N-(5-methyl-2-thenyl)formaldimine in the molar ratio of about 1:1 in aqueous solution in a manner similar to that described in'Example VII. Ijhe product, upon neutralization with, aqueous caustic soda, separated from the aqueous solution as an oil that could not be crystallized.

Example IX About .196 parts by weight of Z-methylthiophene (about 2 moles) and about 108 parts by weight of ammonium chloride (about 2 moles) were mixed and about 4 moles of formaldehyde as an aqueous 36 per cent solution added thereto. The'temperature of the mixture fell to about 15 C. and was allowed to return to ambient temperatures (about 25 C.) whilst stirring the reaction mixture. After one hour the temperature had risen to 32 C.,- indicating the generation of a heat of reaction. The temperature was held at 35-36 C. for about 1.5 hours by means of external cooling. Stirring of the reaction mixture was continued for about one hour longer until the temperature fell to about 30 C. A mass of crystals formed which was filtered off. These crystals were recrystallized from hot water after separating the di-(5-methyl-2-thieny1) methane. The residue was neutralized with aqueous sodium hydroxide, extracted with benzene, the henzene evaporated on a steam bath and the residue subjected to distillation. The N-(5-methyl- 2-thenyl) formaldimine distilled at 110-130 C. at a pressure of 6 millimeters of mercury- Example X Example IX was repeated using 2 moles each of Z-methylthiophene, formaldehyde (aqueous solution) and ammonium chloride. A 50 per cent yield of di-(E-methyl-Z-thenyl)amine hydrochloride together with about 11 parts by weight of benzene-soluble, water insoluble product which had a pleasant alcohol-like odor and contained 5-methyl-2-thenyl alcohol. The filtrate was neutralized with aqueous sodium hydroxide, dissolved in ether, and about 90 per cent of the ether removed by distillation. Alcohol was then added to the solution and the mixture cooled in an ice bath and seeded with crystals of N-(5- methyl-2 -thenyl)formaldimine: By this method a 30 per cent yield (based on formaldehyde) of N-(5-methyl-2-thenyl)formaldimine was obtained together with a residue produced upon removal of the ether-alcohol solvent.

Example XI About one mole of Z-methylthiophene, about one mole of ammonium chloride and about 2 moles of formaldehyde (aqueous solution) were mixed together and the general procedure of Example X followed, with the exception that the temperature was held at 27-30 C. Only 0.14 mole of di-(5-methyl-2-thenyl) amine, 5 parts by weight of benzene-soluble material, 0.19 mole of N-(5-methyl-2-thenyl)formaldimine and 41 parts by weight of residue which crystallized upon further cooling, were obtained.

Example XII About 10 parts by weight of urea (0.16 mole) were added to about parts by weight of the solution of the reaction mixture obtained in Example III. The clear solution was warmed on the steam bath and crystals quickly began to precipitate. After about 30 minutes the mixture was cooled and filtered. The crystals were digested with hot alcohol, filtered and dried. These crystals gave a positive Beilstein test for chlorine, melted at 235 C. (uncorrected block method) with decomposition, and could not be redissolvedn wat co o be zene or ch oro o m. The.

7? product contained 9128 p' r centsulfur', 33.35 per cent nitrOgen and-BII percent-chlorine.

EwampleXIII About 100 parts byweightof the aqueous reaction product obtained in' Example III was added to about 15' parts byiweight of styrene and the mixture heated at' reflux (87-90 Ci) with adequate stirring for 4 hours. When the agitation. was stopped, an oily layer separated out. The oily layer wasseparated by deoantation and washed with per cent aqueous'sodium hydroxide solution. The washed oil was dissolved in benzene and the benzene evaporated; A dark viscous oil containing 15.76 per cent sulfur and 3.95 per cent nitrogen wasobtained.

ErampleXV About 10 parts by weight each ofstyrene and the" aqueous reaction product obtained in Example'III' (free form'aldimine) were heated together as in' ExampleXIII for about 8 hours. The resultant copolymer was similar to that described in Example XIII.

Example: XVI

About 25 parts by weight of liquid reaction product containing free formaldimine obtained in Example IV was dissolved in about 160-parts by weight of-carbon tetrachloride; Tothe solution about 10 parts by Weight of boron trifluorideetherate-was added. The mixture was refluxed for about 2 hours. The product was a hard; brittle resin which could not be dissolved in ben= zone or other common solvents; Treatment with boiling water failed to change the consistency of the product.

Example XVII About 8 to 10 parts by weight'of N-(-2-thenyl) formaldimine were added to aboutbv arts by. Weight of phenol. A heat of reaction was noted and after warming for about 30-.minutes on a steam bath at about 100 C. no odor'of phenol could be detected. The product was a-viscous yellow oil.

Example. XVIII About 10 parts by. weight. of anilinexwere added to about 75 parts by weight of the aqueous reaction mixture obtained in Example III. A precipitate formed immediately and a heat of reaction was noted. The precipitate was resinous and could not be dissolved in any common solventafter being washed and digested in 10 per: cent aqueous sodium hydroxide solution. The light red, resinous product hada sulfur. content of 6.4

per cent and a nitrogen content of.5.-19 per cent.

Example XIX Bis-2,5- (methyleneiminometh'yl) thiophene was prepared in the following manner. About 45 parts by weight of an aqueous 36%so1ution' of formaldehyde (about 0. 5 1'nole of fo'rmaldehyde) (about: 0107' 8 andaboutlk': partsby-"weight oriammonium chloride (about 0.3 mole) were added to about 35 partsvby. weight of N-(Z-thenybformaldimine (about 0.3 mole). The mixture so produced was stirred for: about one L hour at: 7 0 C., i cooled to. room temperature and extracted with ether. Evaporationof: theextract yielded about 8 parts by weight of 2-thiophenealdehyde which was identified as the semicarbazone. Thewater-soluble amines were obtained by treating the aqueous reaction mixture after extraction with other with about 11 parts by'weight of sodium hydroxide (about.0.25 mole) as a 20% aqueous solution and extracting the aqueous mixture with ether. Evaporation of the ether extract yielded 31- parts' by weight of a product which analyzed as follows: nitrogen, 13.63%; sulfur, 21.22%. Since'the calculated values for the N- (2- thenyl) formaldimine are nitrogen, 11.20%; sulfur, 25.60%; the observed values represent an increase in the nitrogen concentration and a decrease in the sulfur concentration. However, bis- 2,5- (methyleneiminomethyl) thiophene,

contains 16.93% nitrogen and 19.27% sulfur. The observed values for nitrogen and sulfur indicate that the product obtained byevaporation of the ether extract of the causticized aqueous solution a mixture: of bis-2,5-(methyleneiminomethyl) thiophene and N- (2-thenyl) formaldimine containing about w-eight percent of each. Oxidation. of a sample of such a mixture with alkaline permanganate gave a mixture of. Z-thiophenecarboxylic acid (from thef-ormaldimine) and 2,5-thiophenedicarboxylic acid from the iminomethylthiophene;

Example XX N- (5-tertiarybutyl-Z-thenyl) formaldimine in the form of. av trimer has been prepared in a manner analogous to that described hereinbefore by reacting 5-tertiarybutylthiophene, formaldehyde and ammonium chloride with sulfur dioxide'gas at C. The product'was obtained as .acrystalline still residue after topping to remove. unreacted 5-tertiarybutylthiophene. still residue was recrystallized from ethanol. The molecular weight of. the recrystallized material was determined by the freezing point meth-- od in cyclohexane and' found-to be 512 (calcu- J latedmolecular weight for the trimer is 543).

Analysis of the recrystallized material yielded 7 the following results:

For CroHreNS Calculated Found Per Cent Carbon..- 65. 99 Per CentHydrogen; 8. 28 Per. Cent Nitrogen; 7. 92

In the recovery of N-(2-thenyDformaldimine by distillation fromthe reaction mass it has been observed that the product distilled in the anticipated range of the'monomeric material but, upon cooling after condensation, it'became quite viscous and behaved; as a higher molecular-weight compound; i.-e.- a polymer. It wasalsocbserved thatduring distillation it was necessary to super heat the still'containing'the reaction mass about- 60 to-80 CL, above theobserved boilingpoint The of the monomeric formaldimine. This is indicative of either a highly associated compound or a polymeric material. Redistillation of N-(2- thenyDformaldimine into a series of fractions gave a series of liquid portions that crystallized in a few weeks to a product that melted at 56 to 565 C. and yielded analyses conforming to CsHvSN. Thus, it appears that N-(2-thenyl)- formaldimine exists in two forms, a liquid form which consistently has a molecular weight of 256 in boiling benzene (a dimer would have a molecular weight of 250) and a crystalline form having a molecular weight of 368 in boiling benzene and a molecular weight of 381 by the freezing point method in cyclohexane. (The calculated molecular weight for the dimer is 375.) Of course, it is possible that the liquid form is a mixture of monomer and trimer.

It has also been observed that traces of 2-thenylamine inhibit the polymerization of the formaldimine. Several distillations of a sample of N-(Z-thenyl)formaldimine yielded a product that polymerized, with an evolution of considerable heat, to a clear solid resin. The polymer depolymerized during a period of about six weeks to a fluid oil having a molecular weight corresponding to a dimer.

Other physical constants of the liquid form of N- (2-thenyl) formaldimine are:

1. Kinematic viscosity in centistokes:

At 100 F., 143.1 At 130 F., 40.3 At 210 F., 5.94

2. Density 3. Molar refractivity Found45.7

Calculated-43.9

There are many indications that the N-(5- methyl 2 thenyl) formaldimine is a trimer. Thus, for example, the molecular weight, by the freezing point method, in cyclohexane is 401 (calculated for the trimer, 417). On the other hand, the molecular weight in boiling benzene is 343 indicating that at that temperature the material is either a mixture of dimer and trimer or that the material is beginning to depolymerize.

From the foregoing it would appear that the thenyl formaldimines exist as monomers or polymers dependent upon the temperature.

From the foregoing it will be recognized by those skilled in the art that the copolymerization of thenylformaldimines with substances known to co-polymerize or to have active hydrogens has been illustrated. It is to be noted that in the condensations involving thenylformaldimines and substance capable of co-polymerizing or having at least one hydrogen of pronounced reactivity the reaction may be carried out without the addition of a catalyst or in the presence of catalysts of the classes consisting of clays, strong mineral acids such as phosphoric acid, boron trifluoride per se or as a complex etc.

I claim:

1. A method for obtaining bis-2,5-(methyleneiminomethyllthiophene which comprises reacting N-(Z-thenyl) formaldimine, formaldehyde and ammonium halide in substantiall equimolecular proportions at about '70 degrees centigrade, to obtain a mixture of thiophenealdehyde, unreaoted formaldimine and said 2,5-

(methyleneiminomethyl)thiophene, separating said thiophene aldehyde from said reaction mixture, causticizing said reaction mixture, extracting said causticized reaction mixture with a solvent, and evaporating said solvent.

' 2. Bis-2,5-(methyleneiminomethyl) thiophene.

3. The reaction product at 70 degrees centigrade of equimolecular proportions of N-(2 thenyl)formaldimine, ammonium halide and formaldehyde which reaction product is oxidizable with alkaline permanganate to 2,5-thiophenedicarboxylic acid.

4. Poly-N-(2-thenyl)formaldimine having in the liquid form an average molecular weight in boiling benzene of 250 to 256, a kinematic viscosity at degrees Fahrenheit of 143.1 centistokes, at degrees Fahrenheit of 40.3 centistokes and at 210 degrees Fahrenheit of 5.94 centistokes, a density,

of 1.2026 and molar refractivity of 45.7, and having in the crystalline form a melting point of 56 to 56.5 degrees centigrade and a molecular weight in boiling benzene of 368 to 375 and a molecular weight of 375 to 381 by the freezing point method in cyclohexane.

5. Poly-N-(5-methyl 2 -thenyl) formaldimine having a molecular weight, by the freezing point method, in cyclohexane of about 401 to 417 and a molecular weight in boiling benzene of about 343.

6. Poly-N-(5-tertiary butyl-2-thenyl)formaldimine having a melting point of 106 to 106.5 degrees centigrade, having a molecular weight, by the freezing point method, in cyclohexane of 512 to 543 and containing 65.99 to 66.30 per cent carbon, 8.28 per cent hydrogen and 7.74 to 7.92 per cent nitrogen.

7. A method of preparing an N-(Z-thenyD- formaldimine which comprises mixing ammonium chloride and aqueous formaldehyde, adding a member of the group consisting of thiophene and thiophene having at least one unsubstituted nuclear alpha carbon and not more than three substituents selected from the group consistin of alkyl, aryl, alkaryl, aralkyl and halogens having a molecular weight greater than 38, raising the temperature of the reaction mix-- ture so formed to not exceed about 70 0., holding said reaction mixture at said reaction temperature until the heat of reaction has subsided, lowering the temperature of said reaction mixture to ambient temperature, separating the aqueous layer, neutralizing said aqueous layer to produce free formaldimine and recovering said formaldimine.

8. A method of preparing an N-(Z-thenyD- formaldimine which comprises mixing ammonium chloride and aqueous formaldehyde adding a member of the group consisting of thiophene and thiophene having at least one unsubstituted nuclear alpha carbon and not more than three substituents selected from the group consisting of alkyl, aryl, alkaryl, aralkyl and halogens havin a molecular weight greater than 38, raising the temperature of the reaction mixture so formed to that at which a reaction is initiated, holding the temperature of said reaction mixture at said temperature at which a reaction is initiated until the heat of reaction has subsided, lowerin the temperature of such reaction mixture to room temperature, separating the aqueous layer, neutralizing said aqueous 11 layer ,.to ':produce 1 free jformaldimine, and necov- UNITED STATES VA'PATE-NTS ering :said :iormaldimine. Number 7 Name Date HQWARDDwHARTOUGH- 2,114,121 Bender Apr '12, 1938 F 1 1 REFERENCES CITED 5 ,4 Caesar Nov. 2, 948 The following references are of record in the REFERENCES 7 file of this patent: Adams: Organic Reactions, v01. 1, pp. 304, 

7. A METHOD OF PREPARING AN N-(2-THENYL)FORMALDIMINE WHICH COMPRISES MIXING AMMONIUM CHLORIDE AND AQUEOUS FORMALDEHYDE, ADDING A MEMBER OF THE GROUP CONSISTING OF THIOPHENE AND THIOPHENE HAVING AT LEAST ONE UNSUBSTITUTED NUCLEAR ALPHA CARBON AND NOT MORE THAN THREE SUBSTITUENTS SELECTED FROM THE GROUP CONSISTING OF ALKY, ARYL, ALKARYL, ARALKYL AND HALOGENS HAVING A MOLECULAR WEIGH GREATER THAN 38, RAISING THE TEMPERATURE OF THE REACTION MIXTURE SO FORMED NOT EXCEED ABOUT 70* C., HOL 